Use of wait period to obtain on-demand system information for wireless networks

ABSTRACT

According to an example implementation, a method may include transmitting, by a user device to a base station in a wireless network, a system information request for on-demand system information during a random access procedure, where the system information request is a request for one or more parameters that enable the user device to communicate in the wireless network, receiving, by the user device from the base station, an indication of a wait period in which the user device waits before obtaining the on-demand system information, waiting, by the user device, a time duration during the wait period, and monitoring, by the user device after expiration of the wait period, a system information window in which a system information message having the on-demand system information is broadcasted by the base station.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.16/624,701 filed on Dec. 19, 2019, which in turn is a 371 application ofInternational Patent Application No. PCT/EP2018/063450 filed May 23,2018, which claims priority benefit to U.S. Non-Provisional patentapplication Ser. No. 15/632,220, filed on Jun. 23, 2017, now U.S. Pat.No. 10,462,706, the disclosures of which are incorporated by referenceherein in their entirety.

TECHNICAL FIELD

This description relates to communications, and in particular, to use ofa wait period to obtain on-demand system information for wirelessnetworks.

BACKGROUND

A communication system may be a facility that enables communicationbetween two or more nodes or devices, such as fixed or mobilecommunication devices. Signals can be carried on wired or wirelesscarriers.

An example of a cellular communication system is an architecture that isbeing standardized by the 3^(rd) Generation Partnership Project (3GPP).A recent development in this field is often referred to as the long-termevolution (LTE) of the Universal Mobile Telecommunications System (UMTS)radio-access technology. E-UTRA (evolved UMTS Terrestrial Radio Access)is the air interface of 3GPP's Long Term Evolution (LTE) upgrade pathfor mobile networks. In LTE, base stations or access points (APs), whichare referred to as enhanced Node AP (eNBs), provide wireless accesswithin a coverage area or cell. In LTE, mobile devices, or mobilestations are referred to as user equipments (UE). LTE has included anumber of improvements or developments. 5G (or 5^(th) generation)wireless networks are also being developed.

In LTE, the system may include an on-demand system information (SI)delivery mechanism in which on-demand SI is transmitted to UEs. Forinstance, when an UE is attempting to access the network, the UE canrequest on-demand SI during a random access procedure. The UE receivesan acknowledgment from the base station in response to the on-demand SI.Then, the base station transmits an SI message to the UE during an SIwindow that contains one or more parameters in the form of one or moreblocks to enable the UE to communicate in the wireless network. However,the base station is not mandated to transmit SI messages when requested.For instance, the base station may be facing a congestion in thedownlink channel or other transmissions are given priority overrequested SI messages, and the base station may not be able to promptlytransmit an SI message to the requesting UE within the next one or moreSI windows. In such situations, the UE may re-attempt the SI request,which may load the random access channel (RACH) since the base stationwill not provide the requested SI before a certain time.

In LTE, a backoff indicator field can be signaled by the network as partof a media access control (MAC) sub-header in a random-access channel(RACH) response. With respect to a value of the backoff indicator, theUE may select a random backoff time according to a uniform distributionbetween 0 and the backoff parameter corresponding to the signaledbackoff indicator. The backoff time is applied only if the random accessresponse (RAR) reception is considered not successful, which occurs ifnone of the received RARs contain a Random Access Preamble identifier(RAPID) corresponding to the transmitted RA preamble. As such, thisbackoff indicator cannot be applied by the UEs that have successfullyreceived a RAR. In this case, the UEs that have received an ACK in theRAR will attempt to decode the SI message in the next SI window, and ifthe SI message is not delivered, the UEs will re-send new SI requests,which may cause congestion on the network.

SUMMARY

According to an example implementation, a method may includetransmitting, by a user device to a base station in a wireless network,a system information request for on-demand system information during arandom access procedure, where the system information request is arequest for one or more parameters that enable the user device tocommunicate in the wireless network, receiving, by the user device fromthe base station, an indication of a wait period in which the userdevice waits before obtaining the on-demand system information, waiting,by the user device, a time duration during the wait period, andmonitoring, by the user device after expiration of the wait period, asystem information window in which a system information message havingthe on-demand system information is broadcasted by the base station.

In some example implementations, the method may include any one or moreof the following features (or any combination thereof). The systeminformation request may be included within a random access preamblemessage. The method may further include transmitting, by the user deviceto the base station, a random access preamble message, receiving, by theuser device from the base station, a random access response, andtransmitting, by the user device from the base station, a message inresponse to the random access response, the message including the systeminformation request. The indication of the wait period may be includedwith an acknowledgment message in response to the system informationrequest. The method may include re-transmitting the system informationrequest after the wait period. The indication of the wait period mayinclude an index value, and the user device may be configured to obtainthe time duration for the wait period from a wait time table using theindex value. The method may further include comparing the time durationof the wait period to a threshold level, and transmitting, from the userdevice to a different base station in a different cell, a new systeminformation request in response to the time duration of the wait periodbeing above the threshold level. The time duration may be included inthe indication of the wait period, where the time duration is expressedin a unit of time or as a function of system information periodicities.

According to an example implementation, an apparatus comprises at leastone processor and at least one memory including computer instructions,when executed by the at least one processor, cause the apparatus totransmit, by a user device to a base station in a wireless network, asystem information request for on-demand system information during arandom access procedure, where the system information request is arequest for one or more parameters that enable the user device tocommunicate in the wireless network, receive, by the user device fromthe base station, an indication of a wait period in which the userdevice waits before obtaining the on-demand system information, wait, bythe user device, a time duration during the wait period, and monitor, bythe user device after expiration of the wait period, a systeminformation window in which a system information message having theon-demand system information is broadcasted by the base station.

In some example implementations, the apparatus may include any one ormore of the above and/or below features (or any combination thereof).The indication of the wait period may correspond to a plurality of SImessages such that the plurality of SI messages are delayed by the timeduration of the wait period. The computer instructions, when executed bythe at least one processor, may cause the apparatus to transmit, by theuser device to the base station, a random access preamble message,receive, by the user device from the base station, a random accessresponse, and transmit, by the user device from the base station, amessage in response to the random access response, the message includingthe system information request. The indication of the wait period may beincluded with an acknowledgment message in response to the systeminformation request. The computer instructions, when executed by the atleast one processor, may cause the apparatus to re-transmitting thesystem information request after the wait period. The indication of thewait period may include a bit indicating the user device to wait, andthe time duration of the wait period is indicated by minimum systeminformation broadcasted by the base station. The computer instructions,when executed by the at least one processor, may cause the apparatus tocompare the time duration of the wait period to a threshold level, andtransmit, by the user device to a different base station in a differentcell, a new system information request in response to the time durationof the wait period being above the threshold level. The indication ofthe wait period may be included within minimum system informationbroadcasted by the base station, and the user device may wait the timeduration of the wait period before transmitting the system informationrequest to the base station. The indication of the wait period may beincluded within a random access channel (RACH) response.

According to an example implementation, a computer program producthaving a computer-readable storage medium and storing executable codethat, when executed by at least one processor, is configured to causethe at least one processor to receive, by a base station from a userdevice in a wireless network, a system information request for on-demandsystem information during a random access procedure, where the systeminformation request is a request for one or more parameters that enablethe user device to communicate in the wireless network, determine, by abase station, a delay condition for transmitting system informationmessages to one or more user devices, transmit, by the base station tothe user device, an indication of a wait period in which the basestation waits before broadcasting a system information message havingthe on-demand system information in response to the determination of thedelay condition, and broadcast, by the base station to the user device,the system information message during a system information window afterthe wait period.

In some example implementations, the computer program product mayinclude any one or more of the above and/or below features (or anycombination thereof). The system information request may be includedwithin a random access preamble message, and the indication of the waitperiod may be included within an acknowledgment of the random accesspreamble message. The executable code that, when executed by the atleast one processor, is configured to cause the at least one processorto receive, by the base station from the user device, a random accesspreamble message, transmit, by the base station to the user device, arandom access response, and receive, by the base station from the userdevice, a message in response to the random access response, where themessage may include the system information request, and the indicationof the wait period may be included within an acknowledgement of themessage. The executable code that, when executed by the at least oneprocessor, is configured to cause the at least one processor toperiodically broadcast, by the base station, minimum system informationduring a system information window, where the minimum system informationmay include the indication of the wait period.

According to an example implementation, a method includes transmitting,by a user device to a base station in a wireless network, a systeminformation request for on-demand system information during a randomaccess procedure, where the system information request is a request forone or more parameters that enable the user device to communicate in thewireless network, receiving, by the user device from the base station,an indication of a wait period in which the user device waits beforeobtaining the on-demand system information, and waiting, by the userdevice, during the wait period in which the user device can expect toreceive the on-demand system information.

According to example implementations, the method may include one or moreof the above/below features (or any combination thereof). The method mayinclude retransmitting, by the user device to the base station after thewait period, the system information request during the random accessprocedure. The system information request may be included within arandom access preamble message. The method may further includetransmitting, by the user device to the base station, a random accesspreamble message, receiving, by the user device from the base station, arandom access response, and transmitting, by the user device to the basestation, a message in response to the random access response, where themessage includes the system information request. The indication of thewait period may be included with an acknowledgment message in responseto the system information request. The indication of the wait period maybe included within minimum system information broadcasted by the basestation. The indication of the wait period may be included within arandom access channel (RACH) response. The indication of the wait periodmay include an index value, and the user device may be configured toobtain the time duration for the wait period from a wait time tableusing the index value. The indication of the wait period may include atime duration expressed as a function of system informationperiodicities. The method may further include considering, by the userdevice, a cell of the wireless network as barred and camping anothercell.

The details of one or more examples of implementations are set forth inthe accompanying drawings and the description below. Other features willbe apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a wireless network according to an exampleimplementation.

FIG. 2 is a block diagram of a base station configured to execute randomaccess and provide system information to a user device according anexample implementation.

FIG. 3 illustrates an example of a communication diagram between thebase station and the user device for providing the system informationaccording to an example implementation.

FIG. 4 illustrates an example of a communication diagram between thebase station and the user device that uses a wait period for MSG3-basedsystem information requests according to an example implementation.

FIG. 5 illustrates an example of a communication diagram between thebase station and the user device that uses a wait period for MSG1-basedsystem information requests according to an example implementation.

FIG. 6 illustrates an example of a communication diagram between thebase station and the user device that uses a wait period for MSG1-basedor MS3-based system information requests according to an exampleimplementation.

FIG. 7 is a flow chart illustrating operations of the user deviceaccording to an example implementation.

FIG. 8 is as flow chart illustrating operations of the base stationaccording to an example implementation.

FIG. 9 is a flow chart illustrating operations of a user deviceaccording to an example implementation.

FIG. 10 is a block diagram of a wireless station according to an exampleimplementation.

DETAILED DESCRIPTION

According to example implementations, the network configures the userdevices to back off from sending system information (SI) requests for acertain time duration to prevent the user devices from sending SIrequests multiple times before the network plans to provide the SI. Forexample, when the base stations needs to defer the transmission ofrequested SI messages, according to the example implementations, thebase station communicates an indication of a wait period to the userdevices, which indicates to back off (or wait) for a certain timeduration, before monitoring the SI window for their requested SImessages or before re-transmitting a new SI request. For instance, thewait period indicates that the requested SI will not be available untilafter the wait period. Also, upon receipt of the wait period, if theuser device determines that the wait period is longer than a thresholdamount, the user device may consider the cell as barred, and send arandom access (RA) request/SI request to another base station in adifferent cell.

The base station may determine that there is congestion in the downlinkor that high priority information transmission is prioritized over therequested SI message transmission, and, based on that determination, thebase station may configure the wait period for all SI messages, for agroup of SI messages, or SI message specific. In some examples, the basestation determines a time duration for the user devices to wait for thedelayed SI messages, and includes that time duration in the indicationof the wait period. The time duration may be expressed in a unit of time(e.g., milliseconds) or as a function of SI periodicities. In someexamples, the indication of the wait period includes an index value, andthe user device determines the time duration of the wait period based ona wait time table (or tables) specified in the specification and theindex value. For example, index 1 may correspond to a wait period of xmilliseconds. Knowing the wait time table and the index value, the userdevice can fetch the time duration for the wait period. In someexamples, the indication of the wait period includes one bit indicatingthe user device to wait, and the time duration may be indicated by theminimum SI broadcasted by the base station.

The SI requested by the user devices may be considered on-demand SI(since it is available upon a SI request made by the user device). Theon-demand SI may consist of a wide variety of information such as interfrequency selection (or re-selection) parameters, multimediabroadcast/multicast service (MBMS) parameters, positioning information,and/or configuration information for emergency/public warning systems,for example. Also, the SI may include minimum SI, which is periodicallybroadcasted by the base station. The minimum SI may include parametersfor initial access such as RA parameters and scheduling information forthe remaining system information block (SIB) types such as SIperiodicity, and SI window information. The network may decide which SIis made available for on-demand provisioning and which SI is madeavailable for periodic broadcasting.

Before the user device sends an SI request, the user device determineswhether the SI that is required by the user device is available in thearea and whether the SI is broadcasted or not. For instance, thescheduling information in the minimum SI may include an indicator thatindicates whether the concerned SI block is periodically broadcasted orprovided on-demand. If the minimum SI indicates that the SI block is notbroadcasted, then the user device does not assume that this SI block isperiodically broadcasted in its SI window at every SI periodicity.Therefore, the user device may send an SI request to obtain this SIblock.

In order to obtain on-demand SI (e.g., SI that is not made availableduring periodic broadcasting), a user device may send a RA based SIrequest for one or more SI messages (each SI message containing adifferent set of SIBs). In some examples, the RA based SI request is arequest for one SI message. In some examples, the RA based SI request isa request for more than one SI messages.

In some examples, the RA based SI request is a message 1 request(MSG1-based SI request). For example, during an RA procedure, the userdevice sends a random access channel (RACH) preamble message (MSG1)having an embedded SI request. In some examples, one RACH preamble canbe used to request multiple SI messages. In response, the user devicereceives an ACK RACH response that includes an indication of the waitperiod. The ACK RACH response is an ACK to confirm receipt of the RACHpreamble message. The ACK RACH response may also include an RACHpreamble identifier (e.g., an identifier corresponding to the preamblesequence to confirm that this response corresponds to the RApreamble/request), but may not include other typical RACH parameterssuch as uplink (UL) grant (e.g., a grant resource for UL transmission bythe user device), CRNTI (e.g., assignment of cell radio networktemporary identifier), TAI (e.g., timing advance for the user device touse for the UL transmission), and/or a backoff indicator. In someexamples, if the user device receives a NACK RACH response, the userdevice may ignore the wait period, and re-transmit its SI request. Inanother example, if the user device receives a NACK RACH response, theuser device may apply the wait period before re-transmitting its SIrequest if the wait period is indicated in the ACK RACH response (MSG2).

In other examples, the RA based SI request is a message 3 request(MSG3-based SI request). For example, during the RA procedure, the userdevice sends a normal RACH preamble message (MSG1) (e.g., not includingthe SI request in the preamble), and receives an RACH response (MSG2)that includes typical RACH parameters such as the UL grant, RA preambleID, TAI, and CRNTI, etc. Then, the user device sends a message (MSG3)having the SI request. In some examples, the SI request message (MSG3)includes a bit mapped SI message request requesting one or more SImessages. In response, the user device receives an ACK message (MSG4)that includes the indication of the wait period. In some examples, ifthe user device receives a NACK message, the user device may ignore thewait period, and re-transmit its SI request. In another example, if theuser device receives a NACK message, the user device may apply the waitperiod before re-transmitting its SI request if the wait period isindicated in the ACK message (MSG 4).

During the wait period, the user device does not monitor the SIwindow(s), but after the expiration of the wait period, the user devicemonitors the next SI window with the expectation of receiving therequested SI. In some examples, after the expiration of the wait period,the user device may re-send its SI request (e.g., MSG1-based SI requestor MSG3-based SI request). In other examples, upon receipt of theindication of the wait period, the user device may compare the timeduration of the wait period to a threshold level, and if the timeduration of the wait period is greater than the threshold level, theuser device may consider the cell barred, and transmit an RA-based SIrequest to another base station of a different cell.

In some examples, the base station broadcasts the indication of the waitperiod in the minimum SI (which also includes the schedulinginformation). For example, the base station may determine to apply await period to all SI requests, a subset of SI requests, or specifictypes of SI requested by the user devices, and the base station maybroadcast the wait period during an SI window. In this case, uponreceiving the indication of the wait period, the user device behaviormay be the same, e.g., waiting until after the expiration of the waitperiod to listen for its requested SI, re-transmit the SI request,and/or consider the cell barred and transmit a new SI request to adifferent cell. In another example, the user device may wait beforesending the SI request if a wait period is indicated in Minimum SI thatthe user device shall check before sending an SI request. That is theuser device may refrain from sending the first SI request if the waitperiod is indicated in Minimum SI. This approach could be useful tocease the user devices from transmitting at all any SI request if thenetwork is unable to deliver the SI before a wait period.

As a result, the use of the wait period for on-demand SI may decreasethe amount of congestion on the RACH, may provide a means to control theamount of SI requests made by the user devices, and may provide a moreflexible scheduling framework for the on-demand SI messages.

FIG. 1 is a block diagram of a wireless network 130 according to anexample implementation. In the wireless network 130 of FIG. 1 , userdevices 131, 132, 133 and 135, which may also be referred to as mobilestations (MSs) or user equipment (UEs), may be connected (and incommunication) with a base station (BS) 134, which may also be referredto as an access point (AP), an enhanced Node B (eNB) or a network node.At least part of the functionalities of an access point (AP), basestation (BS) or (e)Node B (eNB) may be also be carried out by any node,server or host which may be operably coupled to a transceiver, such as aremote radio head. BS (or AP) 134 provides wireless coverage within acell 136, including to user devices 131, 132, 133 and 135. Although onlyfour user devices are shown as being connected or attached to BS 134,any number of user devices may be provided. BS 134 is also connected toa core network 150 via a S1 interface 151. This is merely one simpleexample of a wireless network, and others may be used.

A user device (user terminal, user equipment (UE)) may refer to aportable computing device that includes wireless mobile communicationdevices operating with or without a subscriber identification module(SIM), including, but not limited to, the following types of devices: amobile station (MS), a mobile phone, a cell phone, a smartphone, apersonal digital assistant (PDA), a handset, a device using a wirelessmodem (alarm or measurement device, etc.), a laptop and/or touch screencomputer, a tablet, a phablet, a game console, a notebook, and amultimedia device, as examples. It should be appreciated that a userdevice may also be a nearly exclusive uplink only device, of which anexample is a camera or video camera loading images or video clips to anetwork. A user device (or UE) may also include an Internet of Things(IoT) user device/UE, such as for example, a narrowband Internet ofThings (NB-IoT) user device/UE.

In LTE (as an example), core network 150 may be referred to as EvolvedPacket Core (EPC), which may include a mobility management entity (MME)which may handle or assist with mobility/handover of user devicesbetween BSs, one or more gateways that may forward data and controlsignals between the BSs and packet data networks or the Internet, andother control functions or blocks.

The various example implementations may be applied to a wide variety ofwireless technologies or wireless networks, such as LTE, LTE-A, 5G,cmWave, and/or mmWave band networks, or any other wireless network. LTE,5G, cmWave and mmWave band networks are provided only as illustrativeexamples, and the various example implementations may be applied to anywireless technology/wireless network.

FIG. 2 is a block diagram of a BS 134 configured to execute RA 105 andbroadcast or signal system information (SI) 111 to enable an UE 131 toaccess and transmit information over the mobile network according to anexample implementation.

In LTE, RA 105 is used for initial access when establishing a radio link(e.g., moving from RRC_IDLE to RRC_CONNECTED), to re-establish a radiolink after radio-link failure, for handover when uplink synchronizationneeds to be established to the new cell, and/or to establish uplinksynchronization if uplink or downlink data arrives when the device is inRRC_CONNECTED and the uplink is not synchronized.

According to RA 105, the UE 131 uses a random access channel (RACH)(e.g., an initial uplink access channel) to access the network duringset-up time. In some examples, the RA 105 has four main steps. In stepone, the UE 131 selects one of 64 available RACH preambles, andtransmits the selected RACH preamble (e.g., MSG1), e.g., at thebroadcasted RACH window. The man purpose of the preamble transmission isto indicate to the base station 134 the presence of a random-accessattempt and to allow the base station 134 to estimate the delay betweenthe base station 134 and the UE 131. The RACH preamble may include apreamble sequence and a cyclic prefix. In step two, the base station 134transmits an RACH response (e.g., MGS2) on the downlink shared channel(DL-SCH). In some examples, the RACH response may include a UL grant(e.g., a grant resource for UL transmission by the UE 131), CRNTI (e.g.,assignment of Cell Radio Network Temporary Identifier), TAI (e.g.,timing advance for the UE 131 to use for UL transmission), andpotentially a backoff indicator. In step three, the UE 131 sends an RRCconnection request message (e.g., MSG3) to the base station 134 usingthe uplink shared channel (UL-SCH). The RRC connection request messagemay include the UE identity and a connection establishment cause. Instep four, the base station 134 transmits a contention resolutionmessage (e.g., MSG4) to the UE 131 whose message was successfullyreceived in step three. The contention resolution message may include anew CRNTI which will be used for further communication. In someexamples, by performing RA 105, the UE 131 may transition from an idle(e.g., an RRC_idle) state with respect to the base station 134, to aconnected (e.g., RRC_connected) state with respect to the base station134, where RRC refers to radio resource control.

The base station 134 is configured to broadcast or signal SI 111 to theUE 131. In LTE, SI 111 is transmitted on the broadcast control (BCCH)logical channel. Generally, BCCH messages are carried on the DL-SCH andtransmitted on the physical downlink shared channel (PDSCH). The SI 111includes a plurality of system information blocks (SIBs). Each SIBincludes a set of parameters. For example, SIB1 may include informationrelated to UE cell access and defines the schedules of other SIBs, SIB2may include radio resource configuration information common for all UEs,SIB3 may include intra-frequency, inter-frequency, and/or inter-RAT cellre-selection, SIB4 may include intra-frequency neighboring cellinformation for intra-LTE intra-frequency cell reselection, and SIBS mayinclude neighbor cell related information for intra-LTE inter-frequencycell-reselection. However, these types of SIBs are merely examples, andthe set of SIBs may include a wide variety of parameters.

A particular SI message broadcasted by the base station 134 may includeone or more SIBs. A different SI message carries a different set ofSIBs. SI messages may be broadcasted during SI windows, e.g., separateSI windows for SI messages, and each window has a periodicity that canbe configured. In one example, the base station 134 may periodicallybroadcast SI message having SIB1 (every 80 ms for example).

FIG. 3 illustrates an example of a communication diagram between thebase station 134 and the UE 131 for transmitting the SI 111. In someexamples, the SI 111 includes minimum SI 113, and other SI 115. In someexamples, the minimum SI 113 may include parameters required for initialaccess to the cell 136, RA parameters, scheduling information for SI 111broadcasted periodically or provisioned on-demand, SI window length, SIperiodicity, and SIB type. In some examples, the other SI 115 can beperiodically broadcasted or acquired on-demand. When the other SI 115 isacquired on-demand, in some examples, it may be referred to as on-demandSI. The other SI 115 may include inter frequency selection (orre-selection) parameters, multimedia broadcast/multicast service (MBMS)parameters, positioning information, and/or configuration informationfor emergency/public warning systems.

In operation 302, the base station 134 may periodically broadcast theminimum SI 113 to the UE 131. In operation 304, the base station 134 maybroadcast periodically (and optionally) one or more SI parameters of theother SI 115 to the UE 131. In operation 306, the UE 131 may transmit anSI request, and, in response to the SI request, the base station 134 maybroadcast one or more SI parameters of the other SI 115 (on-demand SI)or transmit the on-demand SI via dedicated signalling. The UE 131 inRRC_IDLE or RRC_INACTIVE transmits an SI request for the on-demand SIwithout requiring a state transition. For the UE 131 in RRC_CONNECTED,dedicated RRC signalling can be used for the request and delivery of theon-demand SI. It is network decision whether the other SI 115 isbroadcast or delivered through dedicated UE specific RRC signalling. Insome examples, in order to obtain the on-demand SI (e.g., SI that is notmade available during periodic broadcasting), the UE 131 may send a RAbased SI request for one or more SI messages. In some examples, the RAbased SI request is a request for one SI message. In some examples, theRA based SI request is a request for more than one SI messages.

FIG. 4 illustrates an example of a communication diagram between thebase station 134 and the UE 131 that uses a wait period for RAMSG3-based SI requests according to an example implementation.

During the RA 105, in operation 402, the UE 131 sends a normal RACHpreamble message (MSG1), and, in operation 404, receives an RACHresponse (MSG2) that includes typical RACH parameters such as UL grant,RA preamble ID, TAI, and CRNTI, and a potential backoff indicator, etc.Then, in operation 406, the UE 131 sends a message (MSG3) having anembedded SI request. In some examples, the SI request message (MSG3)includes a bit mapped SI message request requesting one or more SImessages. In response, in operation 408, the UE 131 receives an ACKmessage (MSG4) that includes the indication of the wait period. In someexamples, if the UE 131 receives a NACK message, the UE 131 may ignorethe wait period, and re-transmit its SI request.

For example, the base station 134 may determine that is unable toprovide the requested on-demand SI for a period of time. In particular,the base station 134 may determine that there is congestion on thedownlink or that high priority information transmission is prioritizedover the requested SI message transmission, and, based on thatdetermination, the base station 134 may configure the wait period forall SI messages, for a group of SI messages, or a particular SI message.In some examples, the base station 134 determines a certain timeduration for the UE 131 to wait for the delayed SI message, and includesthat time duration in the indication of the wait period. In someexamples, the time duration is expressed as an explicit unit of time(e.g., wait x milliseconds) or a function of SI periodicities (e.g.,wait X SI windows).

In some examples, the indication of the wait period may include anSI-request backoff indicator in the ACK message. In some examples, theSI-request backoff indicator is an index value. The UE 131 may obtainthe time duration (expressed as an explicit unit of time or as afunction of SI periodicities) corresponding to the SI-request backoffindicator. For example, the UE 131 may define or have access to a waittime table defined in the specification. The wait time table may includea set of different time durations, where each time duration correspondsto a different index value. Then, based on the wait time table and theSI-request backoff indicator, the UE 131 may obtain the appropriate timeduration for the wait period. In some examples, the indication of thewait period may include only one bit informing the UE 131 to backofffrom sending an SI request during the wait period. In this example, thebackoff configuration could be defined in the specification. Forexample, upon receiving the backoff bit, the UE 131 may automaticallydetermine the time duration from the specification (e.g., upon receivingthe backoff bit, wait x milliseconds or wait a full scheduling periodbefore attempting to re-request). In other examples, the base station134 may broadcast the time duration for the wait period within theminimum SI 113, and when the UE 131 receives the backoff bit (e.g., inthe ACK message), the UE 131 waits for the amount of time broadcasted bythe base station 134.

If the wait period was not communicated to the UE 131 (but thetransmission of the requested SI message was delayed), the UE 131 mayattempt to re-transmit its RA-based SI request, which may cause the RACHto be loaded. However, with the delivery of the wait period, the UE 131may back off from repeating its SI request. During the wait period, inoperation 410, the UE 131 may not listen or monitor the SI window fortheir requested SI message(s). Also, during the wait period, inoperation 410, the UE 131 would not attempt to repeat its SI request.

In some examples, after the expiration of the wait period, in operation412, the base station 134 broadcasts the SI message specific to the UE'srequest during its next scheduled SI window. For example, SI messagesare broadcasted during SI windows, e.g., separate SI windows for SImessages, and each window has a periodicity that can be configured. Inoperation 414, the UE 131 may monitor the SI window to obtain therequested on-demand SI. In some examples, after the expiration of thewait period, in operation 416, the UE 131 may re-send its SI request(e.g., MSG3-based SI request). In other examples, upon receipt of theindication of the wait period, the UE 131 may compare the duration ofthe wait period to a threshold level, and if the time duration of thewait period is greater than the threshold level, the UE 131 may considerthe cell barred, and transmit an RA-based SI request to another basestation of a different cell.

As indicated above, the RACH response may include a backoff indicator,which is different than the wait period for SI requests. For example, ifa relatively large amount of UEs are attempting to access wireless mediaat the same time, e.g., the RACH, then it can cause collisions, so thebackoff indicator may be used to decrease collisions/interference on theRACH. The RACH response's backoff time is applied only if the RACHresponse is considered not successful, which occurs if none of thereceived RACH responses contain a Random Access Preamble identifier(RAPID) corresponding to the transmitted RA preamble. As such, thisbackoff indicator cannot be applied by the UEs that have successfullyreceived a RACH response. In this case, the UEs that have received anACK in the RACH response will attempt to decode the SI message in thenext SI window, and if the SI message is not delivered, the UEs willre-send new SI requests. As such, the existing backoff indicator may notaddress the problem of unnecessary repeats of SI requests.

FIG. 5 illustrates an example of a communication diagram between thebase station 134 and the UE 131 that uses a wait period for MSG1-basedSI requests according to an example implementation.

For example, during the RA 105, in operation 502, the UE 131 selects adedicated RACH preamble for SI request, and sends the selected RACHpreamble having an embedded SI request. In some example, each RACHpreamble is associated with a different SIB. In some examples, one RACHpreamble can be used to request multiple SI messages. In operation 504,the UE 131 receives an ACK RACH response that includes the indication ofthe wait time. The ACK RACH response is an ACK to confirm receipt of theRACH preamble message. The ACK RACH response may also include an RACHpreamble identifier (e.g., an identifier corresponding to the preamblesequence to confirm that this response corresponds to the RApreamble/request), but may not include other typical RACH parameterssuch as the UL grant, the CRNTI, the TAI, the backoff indicator, etc. Insome examples, if the UE 131 receives a NACK RACH response, the UE 131may ignore the wait period, and re-transmit the MSG1-based SI request.

Similar to the example implementation of FIG. 4 , the indication of thewait period may be expressed in one of a plurality of different optionsas previously explained. For example, the indication of the wait periodin the RACH response may include the time duration of the wait period(e.g., in a unit of time or as a function of SI SI periodicities), anindex value in which the corresponding time duration is specified in thewait time table accessible by the UE 131, or the one bit backoffindicator.

In operation 506, during the wait period, the UE 131 may not listen ormonitor the SI window for their requested SI message(s). Also, duringthe wait period, in operation 410, the UE 131 would not attempt torepeat its SI request. In some examples, after the expiration of thewait period, in operation 508, the base station 134 broadcasts the SImessage specific to the UE's request during the next SI window. Inoperation 510, the UE 131 may monitor the SI window to obtain therequested on-demand SI. In some examples, after the expiration of thewait period, in operation 512, the UE 131 may re-send its SI request(e.g., MSG1-based SI request). In other examples, upon receipt of theindication of the wait period, the UE 131 may compare the duration ofthe wait period to a threshold level, and if the time duration of thewait period is greater than the threshold level, the UE 131 may considerthe cell barred, and transmit an RA-based SI request to another basestation of a different cell.

FIG. 6 illustrates an example of a communication diagram between thebase station 134 and the UE 131 that uses a wait period for MSG1-basedor MS3-based SI requests according to an example implementation.

In operation 602, the UE 131 transmits an MSG1 or MSG3-based SI request(as previously explained with reference to FIGS. 4-5 ). In operation604, the UE 131 may receive an ACK message that acknowledges receipt ofthe SI request. In operation 606, instead of providing the indication ofthe wait period in the ACK message, the base station 134 may broadcastthe indication of the wait period during the broadcasting of the minimumSI 113. The base station 134 may determine to apply a wait period to allSI requests, a subset of SI requests, or specific types of SI requestedby the UEs 131, and the base station 134 may broadcast the wait periodduring an SI window. In this case, upon receiving the indication of thewait period, the UE's behavior may be the same, e.g., waiting untilafter the expiration of the wait period to listen for its requested SI(operation 612), re-transmit the SI request (operation 610), or considerthe cell barred and transmit a new SI request to a different cell(operation 614).

Example 1. FIG. 7 is a flow chart 700 illustrating operation of a userdevice/user equipment (UE) according to an example implementation.

Operation 702 includes transmitting, by a user device to a base stationin a wireless network, a system information request for on-demand systeminformation during a random access procedure, where the systeminformation request is a request for one or more parameters that enablethe user device to communicate in the wireless network. Operation 704includes receiving, by the user device from the base station, anindication of a wait period in which the user device waits beforeobtaining the on-demand system information. Operation 706 includeswaiting, by the user device, a time duration during the wait period.Operation 708 includes monitoring, by the user device after expirationof the wait period, a system information window in which a systeminformation message having the on-demand system information isbroadcasted by the base station.

Example 2. According to an example implementation of the method ofexample 1 and/or FIG. 7 , the system information request is includedwithin a random access preamble message.

Example 3. According to an example implementation of the method of anyof examples 1-2 and/or the method of FIG. 7 , the method may furtherinclude transmitting, by the user device to the base station, a randomaccess preamble message, receiving, by the user device from the basestation, a random access response, and transmitting, by the user deviceto the base station, a message in response to the random accessresponse, where the message includes the system information request.

Example 4. According to an example implementation of the method of anyof examples 1-3 and/or the method of FIG. 7 , the indication of the waitperiod is included with an acknowledgment message in response to thesystem information request.

Example 5. According to an example implementation of the method of anyof examples 1-4 and/or the method of FIG. 7 the method further includesre-transmitting the system information request after the wait period.

Example 6. According to an example implementation of the method of anyof examples 1-5 and/or the method of FIG. 7 , the indication of the waitperiod includes an index value, and the user device is configured toobtain the time duration for the wait period from a wait time tableusing the index value.

Example 7. According to an example implementation of the method of anyof examples 1-6 and/or the method of FIG. 7 , the method furtherincludes comparing the time duration of the wait period to a thresholdlevel, and transmitting, from the user device to a different basestation in a different cell, a new system information request inresponse to the time duration of the wait period being above thethreshold level.

Example 8. According to an example implementation of the method of anyof examples 1-7 and/or the method of FIG. 7 , the time duration isincluded in the indication of the wait period, where the time durationis expressed in a unit of time or as a function of system informationperiodicities.

Example 9. According to an example implementation, an apparatuscomprising at least one processor and at least one memory includingcomputer instructions, when executed by the at least one processor,cause the apparatus to execute the method of any of examples 1-8 and/orthe method of FIG. 7 (and/or one or more operations/features discussedherein).

Example 10. According to an example implementation, a computer programproduct, the computer program product comprising a computer-readablestorage medium and storing executable code that, when executed by atleast one processor, is configured to cause the at least one processorto execute the method of any of examples 1-8 and/or the method of FIG. 7(and/or one or more operations/features discussed herein).

Example 11. An apparatus comprising means for performing the method ofany of examples 1-8 and/or the method of FIG. 7 (and/or one or moreoperations/features discussed herein).

Example 12. According to another example implementation, an apparatusmay include at least one processor and at least one memory includingcomputer instructions, when executed by the at least one processor,cause the apparatus to transmit, by a user device to a base station in awireless network, a system information request for on-demand systeminformation during a random access procedure, where the systeminformation request is a request for one or more parameters that enablethe user device to communicate in the wireless network, receive, by theuser device from the base station, an indication of a wait period inwhich the user device waits before obtaining the on-demand systeminformation, wait, by the user device, a time duration during the waitperiod, and monitor, by the user device after expiration of the waitperiod, a system information window in which a system informationmessage having the on-demand system information is broadcasted by thebase station.

Example 13. According to an example implementation of example 12, theindication of the wait period corresponds to a plurality of SI messagessuch that the plurality of SI messages are delayed by the time durationof the wait period.

Example 14. According to an example implementation of any of examples12-13, the computer instructions, when executed by the at least oneprocessor, cause the apparatus to transmit, by the user device to thebase station, a random access preamble message, receive, by the userdevice from the base station, a random access response, and transmit, bythe user device to the base station, a message in response to the randomaccess response, where the message includes the system informationrequest.

Example 15. According to an example implementation of any of examples12-14, the indication of the wait period is included with anacknowledgment message in response to the system information request.

Example 16. According to an example implementation of any of examples12-15, the computer instructions, when executed by the at least oneprocessor, cause the apparatus to re-transmitting the system informationrequest after the wait period.

Example 17. According to an example implementation of any of examples12-16, the computer instructions, when executed by the at least oneprocessor, cause the apparatus to compare the time duration of the waitperiod to a threshold level, and transmit, by the user device to adifferent base station in a different cell, a new system informationrequest in response to the time duration of the wait period being abovethe threshold level.

Example 18. According to an example implementation of any of examples12-17, the indication of the wait period includes a bit indicating theuser device to wait, and the time duration of the wait period isindicated by minimum system information broadcasted by the base stationa time duration in which the user device waits before re-attempting thesystem information request.

Example 19. According to an example implementation of any of examples12-18, the indication of the wait period is included within minimumsystem information broadcasted by the base station, and the user devicewaits the time duration of the wait period before transmitting thesystem information request to the base station.

Example 20. According to an example implementation of any of examples12-19, the indication of the wait period is included within a randomaccess channel (RACH) response.

Example 21. FIG. 8 is as flow chart 800 illustrating operation of a basestation (BS)/eNB according to an example implementation.

Operation 802 includes receiving, by a base station from a user devicein a wireless network, a system information request for on-demand systeminformation during a random access procedure, where the systeminformation request is a request for one or more parameters that enablethe user device to communicate in the wireless network. Operation 804includes determining, by a base station, a delay condition fortransmitting system information messages to one or more user devices.Operation 806 includes transmitting, by the base station to the userdevice, an indication of a wait period in which the base station waitsbefore broadcasting a system information message having the on-demandsystem information in response to the determination of the delaycondition. Operation 808 includes broadcasting, by the base station tothe user device, the system information message during a systeminformation window after the wait period.

Example 22. According to an example implementation of the method ofexample 21 and/or the method of FIG. 8 , the system information requestis included within a random access preamble message, and the indicationof the wait period is included within an acknowledgment of the randomaccess preamble message.

Example 23. According to an example implementation of the method of anyof examples 21-22 and/or the method of FIG. 8 , the method includesreceiving, by the base station from the user device, a random accesspreamble message, transmitting, by the base station to the user device,a random access response, and receiving, by the base station from theuser device, a message in response to the random access response, wherethe message includes the system information request, and the indicationof the wait period is included within an acknowledgement of the message.

Example 24. According to an example implementation of the method of anyof examples 21-23 and/or the method of FIG. 8 , the method includesperiodically broadcasting, by the base station, minimum systeminformation during a system information window, where the minimum systeminformation includes the indication of the wait period.

Example 25. According to an example implementation, an apparatuscomprising at least one processor and at least one memory includingcomputer instructions, when executed by the at least one processor,cause the apparatus to execute the method of any of examples 21-24and/or the method of FIG. 8 (and/or one or more operations/featuresdiscussed herein).

Example 26. According to an example implementation, a computer programproduct, the computer program product comprising a computer-readablestorage medium and storing executable code that, when executed by atleast one processor, is configured to cause the at least one processorto execute the method of any of examples 21-24 and/or the method of FIG.8 (and/or one or more operations/features discussed herein).

Example 27. An apparatus comprising means for performing the method ofany of examples 21-24 and/or the method of FIG. 8 (and/or one or moreoperations/features discussed herein).

Example 28. FIG. 9 is a flow chart 900 illustrating operation of a userdevice/user equipment (UE) according to an example implementation.

Operation 902 includes transmitting, by a user device to a base stationin a wireless network, a system information request for on-demand systeminformation during a random access procedure, where the systeminformation request is a request for one or more parameters that enablethe user device to communicate in the wireless network. Operation 904includes receiving, by the user device from the base station, anindication of a wait period in which the user device waits beforeobtaining the on-demand system information. Operation 906 includeswaiting, by the user device, during the wait period in which the userdevice can expect to receive the on-demand system information. In thisimplementation, the user device may receive the indication of the waitperiod (according to one or more of the above described examples), andduring the wait period, the user device may expect to receive theon-demand system information from the base station. For example, in thisimplementation, the wait period is a time duration in which the basestation is configured to delivery the on-demand system information.

Example 29. According to an example implementation of the method ofexample 28 and/or the method of FIG. 9 , the method may includeretransmitting, by the user device to the base station after the waitperiod, the system information request during the random accessprocedure.

Example 30. According to an example implementation of the method of anyof examples 28-29 and/or the method of FIG. 9 , the system informationrequest may be included within a random access preamble message.

Example 31. According to an example implementation of the method of anyof examples 28-30 and/or the method of FIG. 9 , the method may furtherinclude transmitting, by the user device to the base station, a randomaccess preamble message, receiving, by the user device from the basestation, a random access response, and transmitting, by the user deviceto the base station, a message in response to the random accessresponse, the message including the system information request.

Example 32. According to an example implementation of the method of anyof examples 28-31 and/or the method of FIG. 9 , the indication of thewait period may be included with an acknowledgment message in responseto the system information request.

Example 33. According to an example implementation of the method of anyof examples 28-32 and/or the method of FIG. 9 , the indication of thewait period may be included within minimum system informationbroadcasted by the base station.

Example 34. According to an example implementation of the method of anyof examples 28-33 and/or the method of FIG. 9 , the indication of thewait period may be included within a random access channel (RACH)response.

Example 35. According to an example implementation of the method of anyof examples 28-34 and/or the method of FIG. 9 , the indication of thewait period may include an index value, and the user device may beconfigured to obtain the time duration for the wait period from a waittime table using the index value.

Example 36. According to an example implementation of the method of anyof examples 28-35 and/or the method of FIG. 9 , the indication of thewait period may include a time duration expressed as a function ofsystem information periodicities.

Example 37. According to an example implementation, an apparatuscomprising at least one processor and at least one memory includingcomputer instructions, when executed by the at least one processor,cause the apparatus to execute the method of any of examples 28-36and/or the method of FIG. 9 , (and/or one or more operations/featuresdiscussed herein).

Example 38. According to an example implementation, a computer programproduct, the computer program product comprising a computer-readablestorage medium and storing executable code that, when executed by atleast one processor, is configured to cause the at least one processorto execute the method of any of examples 28-36 and/or the method of FIG.9 , (and/or one or more operations/features discussed herein).

Example 39. An apparatus comprising means for performing the method ofany of examples 28-36 and/or the method of FIG. 9 , (and/or one or moreoperations/features discussed herein).

FIG. 10 is a block diagram of a wireless station (e.g., AP or userdevice) 1000 according to an example implementation. The wirelessstation 1000 may include, for example, one or two RF (radio frequency)or wireless transceivers 1002A, 1002B, where each wireless transceiverincludes a transmitter to transmit signals and a receiver to receivesignals. The wireless station also includes a processor or controlunit/entity (controller) 1004 to execute instructions or software andcontrol transmission and receptions of signals, and a memory 1006 tostore data and/or instructions.

Processor 1004 may also make decisions or determinations, generateframes, packets or messages for transmission, decode received frames ormessages for further processing, and other tasks or functions describedherein. Processor 1004, which may be a baseband processor, for example,may generate messages, packets, frames or other signals for transmissionvia wireless transceiver 1002A or 1002B. Processor 1004 may controltransmission of signals or messages over a wireless network, and maycontrol the reception of signals or messages, etc., via a wirelessnetwork (e.g., after being down-converted by wireless transceiver 1002,for example). Processor 1004 may be programmable and capable ofexecuting software or other instructions stored in memory or on othercomputer media to perform the various tasks and functions describedabove, such as one or more of the tasks or methods described above(e.g., any of the operations of the timing diagrams and flowcharts ofthe figures). Processor 1004 may be (or may include), for example,hardware, programmable logic, a programmable processor that executessoftware or firmware, and/or any combination of these. The processor1004 may include one or more processors coupled to a substrate. Usingother terminology, processor 1004 and transceiver 1002 together may beconsidered as a wireless transmitter/receiver system, for example.

In addition, referring to FIG. 10 , a controller (or processor) 1008 mayexecute software and instructions, and may provide overall control forthe station 1000, and may provide control for other systems not shown inFIG. 10 , such as controlling input/output devices (e.g., display,keypad), and/or may execute software for one or more applications thatmay be provided on wireless station 1000, such as, for example, an emailprogram, audio/video applications, a word processor, a Voice over IPapplication, or other application or software.

In addition, a storage medium may be provided that includes storedinstructions, which when executed by a controller or processor mayresult in the processor 1004, or other controller or processor,performing one or more of the functions or tasks described above.

According to another example implementation, RF or wirelesstransceiver(s) 1002A/1002B may receive signals or data and/or transmitor send signals or data. Processor 1004 (and possibly transceivers1002A/1002B) may control the RF or wireless transceiver 1002A or 1002Bto receive, send, broadcast or transmit signals or data.

The embodiments are not, however, restricted to the system that is givenas an example, but a person skilled in the art may apply the solution toother communication systems. Another example of a suitablecommunications system is the 5G concept. It is assumed that networkarchitecture in 5G will be quite similar to that of the LTE-advanced. 5Gis likely to use multiple input-multiple output (MIMO) antennas, manymore base stations or nodes than the LTE (a so-called small cellconcept), including macro sites operating in co-operation with smallerstations and perhaps also employing a variety of radio technologies forbetter coverage and enhanced data rates.

It should be appreciated that future networks will most probably utilisenetwork functions virtualization (NFV) which is a network architectureconcept that proposes virtualizing network node functions into “buildingblocks” or entities that may be operationally connected or linkedtogether to provide services. A virtualized network function (VNF) maycomprise one or more virtual machines running computer program codesusing standard or general type servers instead of customized hardware.Cloud computing or data storage may also be utilized. In radiocommunications this may mean node operations may be carried out, atleast partly, in a server, host or node operationally coupled to aremote radio head. It is also possible that node operations will bedistributed among a plurality of servers, nodes or hosts. It should alsobe understood that the distribution of labour between core networkoperations and base station operations may differ from that of the LTEor even be non-existent.

Implementations of the various techniques described herein may beimplemented in digital electronic circuitry, or in computer hardware,firmware, software, or in combinations of them. Implementations mayimplemented as a computer program product, i.e., a computer programtangibly embodied in an information carrier, e.g., in a machine-readablestorage device or in a propagated signal, for execution by, or tocontrol the operation of, a data processing apparatus, e.g., aprogrammable processor (e.g., a processor coupled to a substrate), acomputer, or multiple computers. Implementations may also be provided ona computer readable medium or computer readable storage medium, whichmay be a non-transitory medium. Implementations of the varioustechniques may also include implementations provided via transitorysignals or media, and/or programs and/or software implementations thatare downloadable via the Internet or other network(s), either wirednetworks and/or wireless networks. In addition, implementations may beprovided via machine type communications (MTC), and also via an Internetof Things (IOT).

The computer program may be in source code form, object code form, or insome intermediate form, and it may be stored in some sort of carrier,distribution medium, or computer readable medium, which may be anyentity or device capable of carrying the program. Such carriers includea record medium, computer memory, read-only memory, photoelectricaland/or electrical carrier signal, telecommunications signal, andsoftware distribution package, for example. Depending on the processingpower needed, the computer program may be executed in a singleelectronic digital computer or it may be distributed amongst a number ofcomputers.

Furthermore, implementations of the various techniques described hereinmay use a cyber-physical system (CPS) (a system of collaboratingcomputational elements controlling physical entities). CPS may enablethe implementation and exploitation of massive amounts of interconnectedICT devices (sensors, actuators, processors microcontrollers, . . . )embedded in physical objects at different locations. Mobile cyberphysical systems, in which the physical system in question has inherentmobility, are a subcategory of cyber-physical systems. Examples ofmobile physical systems include mobile robotics and electronicstransported by humans or animals. The rise in popularity of smartphoneshas increased interest in the area of mobile cyber-physical systems.Therefore, various implementations of techniques described herein may beprovided via one or more of these technologies.

A computer program, such as the computer program(s) described above, canbe written in any form of programming language, including compiled orinterpreted languages, and can be deployed in any form, including as astand-alone program or as a module, component, subroutine, or other unitor part of it suitable for use in a computing environment. A computerprogram can be deployed to be executed on one computer or on multiplecomputers at one site or distributed across multiple sites andinterconnected by a communication network.

Method steps may be performed by one or more programmable processors(e.g., one or more processors coupled to a substrate) executing acomputer program or computer program portions to perform functions byoperating on input data and generating output. Method steps also may beperformed by, and an apparatus may be implemented as, special purposelogic circuitry, e.g., an FPGA (field programmable gate array) or anASIC (application-specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer, chip orchipset. Generally, a processor will receive instructions and data froma read-only memory or a random access memory or both. Elements of acomputer may include at least one processor for executing instructionsand one or more memory devices for storing instructions and data.Generally, a computer also may include, or be operatively coupled toreceive data from or transfer data to, or both, one or more mass storagedevices for storing data, e.g., magnetic, magneto-optical disks, oroptical disks. Information carriers suitable for embodying computerprogram instructions and data include all forms of non-volatile memory,including by way of example semiconductor memory devices, e.g., EPROM,EEPROM, and flash memory devices; magnetic disks, e.g., internal harddisks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROMdisks. The processor and the memory may be supplemented by, orincorporated in, special purpose logic circuitry.

To provide for interaction with a user, implementations may beimplemented on a computer having a display device, e.g., a cathode raytube (CRT) or liquid crystal display (LCD) monitor, for displayinginformation to the user and a user interface, such as a keyboard and apointing device, e.g., a mouse or a trackball, by which the user canprovide input to the computer. Other kinds of devices can be used toprovide for interaction with a user as well; for example, feedbackprovided to the user can be any form of sensory feedback, e.g., visualfeedback, auditory feedback, or tactile feedback; and input from theuser can be received in any form, including acoustic, speech, or tactileinput.

Implementations may be implemented in a computing system that includes aback-end component, e.g., as a data server, or that includes amiddleware component, e.g., an application server, or that includes afront-end component, e.g., a client computer having a graphical userinterface or a Web browser through which a user can interact with animplementation, or any combination of such back-end, middleware, orfront-end components. Components may be interconnected by any form ormedium of digital data communication, e.g., a communication network.Examples of communication networks include a local area network (LAN)and a wide area network (WAN), e.g., the Internet.

While certain features of the described implementations have beenillustrated as described herein, many modifications, substitutions,changes and equivalents will now occur to those skilled in the art. Itis, therefore, to be understood that the appended claims are intended tocover all such modifications and changes as fall within the true spiritof the various embodiments.

What is claimed is:
 1. An apparatus, comprising: at least one processor;and at least one memory including computer instructions that, whenexecuted by the at least one processor, cause the apparatus to: receivean indication including an index value; transmit a random access channelpreamble including a system information request for requesting on-demandsystem information, during a random access procedure; and obtain, byusing the index value, a time duration in which the apparatus expects toreceive the on-demand system information.
 2. The apparatus according toclaim 1, wherein the indication is included in minimum systeminformation.
 3. The apparatus according to claim 1, wherein the timeduration is obtained from a time table by using the index value.
 4. Theapparatus according to claim 1, wherein the apparatus is in an idlemode.
 5. The apparatus according to claim 1, wherein the on-demandsystem information includes one or more system information blocks. 6.The apparatus according to claim 1, wherein the apparatus is configuredto receive the on-demand system information during the time duration. 7.A method comprising: receiving, by a user device, an indicationincluding an index value; transmitting, by the user device, a randomaccess channel preamble including a system information request forrequesting on-demand system information, during a random accessprocedure; and obtaining, by the user device by using the index value, atime duration in which the apparatus expects to receive the on-demandsystem information.
 8. The method according to claim 7, wherein theon-demand system information includes one or more system informationblocks.
 9. The method according to claim 7, wherein the indication isincluded in minimum system information.
 10. The method according toclaim 7, wherein the time duration is obtained from a time table byusing the index value.
 11. The method according to claim 7, wherein theapparatus is in an idle mode.
 12. The method according to claim 7,wherein the apparatus is configured to receive the on-demand systeminformation during the time duration.
 13. A non-transitorycomputer-readable medium comprising instructions encoded thereon which,when executed by an apparatus, cause the apparatus to perform at least:receiving an indication including an index value; transmitting a randomaccess channel preamble including a system information request forrequesting on-demand system information, during a random accessprocedure; and obtaining, by using the index value, a time duration inwhich the apparatus expects to receive the on-demand system information.14. The non-transitory computer-readable medium according to claim 13,wherein the on-demand system information includes one or more systeminformation blocks.
 15. The non-transitory computer-readable mediumaccording to claim 13, wherein the indication is included in minimumsystem information.
 16. The non-transitory computer-readable mediumaccording to claim 13, wherein the time duration is obtained from a timetable by using the index value.
 17. The non-transitory computer-readablemedium according to claim 13, wherein the apparatus is in an idle mode.18. The non-transitory computer-readable medium according to claim 13,wherein the apparatus is configured to receive the on-demand systeminformation during the time duration.